1. To add caffeine.

2. (slang) To drink caffeinated beverages in order to increase energy levels in the body, enhance physical or mental performance, or simply to wake up.

- 2008, Caffeinate With Care: Small Shots Do a Brain Better Than Big Blasts, Mathew Honan, Wired, 04.21.08

3. (slang) To inject tension (usually into a situation) for the amusement of the instigator; to stir things up.

4. (slang) To provoke (as in a person) also for the amusement of the instigator.